Living and Dying Color

Phenomena depends on frequency. Objects tend to emit light at certain preferred frequencies. By studying the Universe in different frequencies, astronomers unveil different populations of objects. Comparison of these frequencies reveal relations between these different populations. The XMM-Newton observatory includes both X-ray and ultraviolet cameras and it allows direct, simultaneous comparison between the ultraviolet-light emitting objects (like young massive stars) and old dead stars which produce X-rays. The
image above shows the result of an XMM observation of M81, a (moderately) active galaxy, which combines a set of ultraviolet images (shown in blue and green) and an X-ray image (shown in red). The dominant X-ray source is located at the center of the galaxy, a supermassive black hole slowly gobbling material. M81's spiral arms glow in blue light emitted from young star forming regions; some X-ray emitting objects are also located there, while others surround the central black hole. Observations such as this one help provide a picture of life and death within galaxies.